the franco-german approach for tr9800034 a

THE FRANCO-GERMAN APPROACH FOR TR9800034A NUCLEAR POWER PLANT IN TURKEY

Fritz Ruess

Nuclear Power International

ÖZET

Nuclear Power International (NPI) firması, 1989 yılında, Siemens ve Framatome firmalarının ortaklığı ilekurulmuştur. Böylece, nükleer alanda, her iki kardeş firmanın 100.000 MWdan fazla kurulu veya ısmarlanmış ka-pasiteye dayalı deneyim birikimleri bu yeni firmada birleştirilmiştir. Biz, Türkiye'deki olası bir nükleer güç projesin-de, Alman Basınçlı Su Reaktör Teknolojisini temel alarak rekabet etmek niyetindeyiz. Yabancı yükleniciler tarafın-da Siemens, Framatome ve GEC-Alsthom firmalarının bulunacağı bir konsorsyum kurulacaktır. Konsorsyumunyabancı ortaklarına ek olarak, mümkün olan en fazla yerel katkıyı sağlamak için, Türk endüstrisini de teklif paketi-ne dahil edeceğiz. Önceki teklifimizdeki yerel pay, kontrat miktarının % 30 kadarını kapsıyordu.

ABSTRACT

Nuclear Power International (NPI) has been established as a joint subsidiary of Siemens and Framatomein 1989, thereby combining the experience accumulated in both parent companies with more than 100,000 MWcapacity installed or on order in nuclear field. We intend to compete in a potential nuclear power project in Turkeyon the basis of the German Pressurized Water Reactor Technology. We intend to establish a Consortium whichon the foreign suppliers side will include Siemens, Framatome and GEC-Alsthom. In addition to the foreign part-ners in the Consortium we will include the Turkish industry in our proposal in order to achieve a maximum possib-le local content, which in our previous proposal was in the range of 30 % of the contract-value.

INTRODUCTION

Nuclear Power International (NPI) has been established as a joint subsidiary of Siemens and

Framatome in 1989, thereby combining the experience accumulated in both parent companies with

more than 100,000 MW capacity installed or on order in the nuclear field.

The basic objectives of NPI are twofold. In the marketing-field, NPI is in charge of marketing

nuclear islands and complete nuclear power plants on the basis of the technologies developed by Fra-

matome in France and by Siemens in Germany.

In the development field, NPI is coordinating the development of a joint Franco-German PWR-

design for the future, called European Pressurized Water Reactor (EPR). This development is pre-

sently being supported by the utilities and the licensing authorities in both countries. It is expected that

nuclear units based on this EPR technology will be under construction by the end of this decade and

the technology can be offered thereafter on the international market.

Projects, which will be executed in the near future require a proven, yet up to date technology,

which is available in France and Germany today.

58

SIEMENS EXPERIENCE IN TURKEY

Siemens as one of NPI's parent companies has a long experience in Turkey, the first Siemens

Company in Turkey was established in 1927. Today, Simko and Türk Siemens, which represent the

Siemens Group in Turkey provide services in almost every branch of electrical and electronic fields

with a staff of nearly 4,000 people.

In the power generation and distribution field, Siemens covers a wide spectrum including lignite

and gas fired conventional power plants, the latest example being the combined cycle plant in Ambar-

lı, where Simko was a consortium member providing supplies and erection service.

More specifically, Siemens nuclear technology has been extensively discussed with TEK and

TAEK during the contract negotiations between 1982 and 1984 for AKKUYU. During this time, the li-

censability of Siemens Pressurized Water Technology in Turkey was investigated in detail and finally

confirmed. A contract was negotiated simultaneously and all technical and contractual details were ag-

reed upon. Even if this this contract could not finally be signed, we believe that the comprehensive

work undertaken during these negotiations represent a valuable asset for any future discussions on a

Nuclear Power Plant in Turkey.

NPI'S PROPOSAL FOR A NUCLEAR POWER PLANT IN TURKEY

On the basis of the experience described above, we intend to compete in a potential nuclear

power project in Turkey on the basis of the German Pressurized Water Reactor Technology. We in-

tend to establish a Consortium which on the foreign suppliers side will include Siemens, Framatome

and GEC-Alsthom. Siemens will be responsible for the design, construction and commissioning of the

Nuclear Island, Framatome will be in charge of the important components in the Nuclear Steam

Supply System such as Reactor Pressure Vessel, Steam Generators and Pressurizer and GEC-

Alsthom will be responsible for the Conventional Island. Thereby we combine not only the extensive

know-how and industrial capabilities but also the financing potentials in France and Germany. In addi-

tion to the foreign partners in the Consortium we will include the Turkish industry in our proposal in

order to achieve a maximum possible local content, which in our previous proposal was in the range

of 30 % of the contract-value. Technically, the proposal will be based on the nuclear side on the Ger-

man "Konvoi" -plants, the latest 4-loop Pressurized Water Reactors commissioned in Germany re-

cently and on the conventional side on the technology of GEC-Altshom with their outstanding experi-

ence in the large nuclear power program in France and in export-projects of the French industry in

Belgium, South-Korea, South-Africa and China. In the frame of thes International Nuclear Technology

Forum, we shall concentrate below on the technical description of the Nuclear Island.

TECHNICAL FEATURES OF THE NUCLEAR ISLAND

With the choice of the Convoy-type 4-loop Pressurized Water Reactor with a thermal output of

3850 MW, resulting in a net electrical output of the plant of approximately 1.360 MW we have combi-

59

ned the advantage of a technology recently licensed under the very stringent German licensing requi-

rements with the economy of scale of large units which on the one hand appears to be necessary for

a competitive energy-generation cost and on the other hand fits to the grid capacity installed in Turkey

by the time the plant will we commissioned.

PLANT LAYOUT

The plant layout of NPI's power plant is characterized by a distinction between site dependent

and site independent buildings. The arrangement of the site independent buildings is selected so that

it fifts practically to any site and so that the site dependent buildings can be easily adjusted to particu-

lar customer's requirements and local conditions (see figure 1).

The reactor building is located almost in the centre of the plot plan, thus keeping interconnec-

ting pipes and cables as short as possible. Good accessibility of the buildings during construction in

ensured, however. The arrangement of the reactor building on the axis of the turbo-generator set pre-

vents damage to safety related systems and components by turbine missiles. Moreover, it reduces the

length of the main steam and feedwater lines to a minimum. The related pilot operated safety and iso-

lation valves are located immediately outside the reactor building in a special compartment, resulting

in a very compact arrangement.

The controlled access area is clearly separated from the non-controlled area and comprises the

reactor building and parts of the reactor auxiliary building. Access is provided via only one central ac-

cess point in the reactor auxiliary building. All secondary systems are arranged in the turbine building

but no systems related to nuclear safety are located there.

REACTOR BUILDING

The primary components in the reactor building are installed in an as low as possible position in

relation to the ground level. The reactor pressure vessel is surrounded by a biological shield which

serves as radiation shield.

The reactor pressure vessel together with the other primary components is surrounded by a fre-

estanding steel containment designed to withstand the accident pressure after LOCA. This freestan-

ding, spherical design provides large laydown space on the operating floor and an easy maintainability

and inspectability. The leak rate at test pressure is specified to 0.25 vol %/d, whereas the real leak

rates achieved are by several factors lower.

The steel shell itself is surrounded by a concrete containment serving as protection against ex-

ternal events and as radiation shield. The space between both forms the annulus. Its atmosphere can

be exhausted via filters, thus reducing the effects to the environment after accidents significantly. The

doses to the general public after design basis accidents as calculated for German site conditions are

under worst case consideration by a factor lower than the permissible limit values.

60

The design of this double containment together with the design of the ventilation systems, mo-

reover, provides the accessibility of the containment even during operation, which contributes to short

annual outage times. The fuel pool is located inside the containment so that the transport ways of the

fuel assemblies during refuelling are the shortest possible ones.

EMERGENCY POWER SUPPLY BUİLDİNGS

In the design of the KONVOI plants, following the German licensing requirements, external

events have to be considered. This led to a clear separation of the switchgear, emergency power

supply and emergency feed functions in different buildings (see figure 3). Each of these buildings is di-

vided into four identical sections, one for each redundancy. The interconnecting pipes and cables are

run in physically separated ducts. As a consequence of this strict separation of functions, only the

emergency feed building, beside the reactor building itself, is needed to be protected against external

events.

The application of this strict separation philosophy furthermore led to a very high redundancy of

emergency power diesel generators. The normal emergency power grid, the so-called D1 net, is supp-

lied by four large diesel generators with 50 % capacity each. It serves all safety related functions.

In addition, four smaller diesel motors drive directly the emergency feedwater pumps and are

connected to generators serving the so-called D2 net, also following the 4x50 % principle. They are lo-

cated in the emergency feed building, thus being protected against external events. This building also

includes the safety related switchgears and the emergency control room.

THE REACTOR COOLANT SYSTEM

The reactor coolant system of KONVOI plants consists of four identical main coolant loops. The

main technical data of the reactor coolant system are given in figure 4. The reactor pressure vessel is

the fixpoint of the primary system. It is made of seamless forged ferritic rings with austenitic cladding.

The utilization of forged rings as base material leads to the omission of any longitudinal welding.

A large water gap reduces the neutron flux to the RPV material in order to ensure a long and

safe life time of this component. All penetrations, for the control rod drives as well as for the incore ins-

trumentation are located at the closure head, so that not bottom penetrations are required. By that,

any leakage below the level of the main coolant nozzles can be ruled out (see figure 5).

The design of the steam generators probably is the most outstanding feature of our plants (see

figure 6). The heating tubes are made of the material Incoloy 800, a material which has proven the

best operating results.

Not only the material selection is decisive for the operating performance of the steam genera-

tors, also the design contributes significantly. The heating tubes are welded to the tubesheet on the

primary side and are twice roller-expanded avoiding the formation of a crevice on secondary side.

They are supported by tube support grids made of austenitic steel. These so-called egg-crate tube

supports consist of two rows of bars which are arranged in two planes at an angle of 120°. This design

61

provides wide flow cross-sections and prevents the deposition of impurities causing damages to the

tubes, known as denting. Furthermore, proper water chemistry specifications for the primary and se-

condary circuit, harmonized with the mateirals involved on both sides, have to be kept.

All these precautions in connection with extensive inservice inspection with especially designed

manipulators led to outstanding operating results concerning the integrity of the steam generator hea-

ting tubes, so that the probability for a primary to secondary leak could be significantly reduced for

nuclear power plants equipped with steam generators manufactured according to our specification.

The main coolant pumps are single-stage centrifugal pumps. As shaft seals theree identical

hydrodynamic seals are used which can be replaced without the necessity of motor removal. The ma-

terial selection for these seals as well as for the bearings was done under the consideration to reduce

the use of antimony to a minimum, thus contributing to an as low as possible radiation exposure to the

operating personnel. A special nitrogen operated stand-still seal is provided in order to prevent loss of

coolant in case of unavailability of reactor auxiliary systems.

The main coolant lines as well as all other primary components and in addition the secondary

side shell of the steam generators are fabricated from forged materials under high quality require-

ments, so that longitudinal welds are omitted and the number of circumferential welds is reduced to a

minimum. This leads to a reduced scope of inservice inspections and in line with that to shorter outa-

ge times and again to reduced personnel exposure. Also the replacement of cobalt base alloys in the

primary circuit by other hard facing materials has contributed to the reduction of personnel exposure.

For the main coolant lines as well as for the main steam and main feedwater lines inside conta-

inment, the LBB-concept (leak before break) is applied which on the basis of careful material selecti-

on, load analysis, inservice inspections and high quality of the manufacturing process excludes a ca-

tastrophic failure of the pressure boundary. On the basis of the LBB concept, only a 0.1 A break has

to be considered as design basis (expect for the emergency core cooling system and for the contain-

ment design, where still a 2 A break is considered) and leads to the omission of pipe whip restraints.

By the avoidance of pipe whip restraints the personnel exposure to the operating personnel accumula-

ted for inservice inspection work at the main coolant loops is reduced by a factor of about 5, since the

whip restraints need not any longer to be dismantled and reassembled for inservice inspection work.

SAFETY ASPECTS

The safety systems are designed to reliably shutdown the reactor and keep it in a safe subcrhi-

cal condition and to remove the residual heat on a long term basis under upset conditions or postula-

ted accidents. The single failure postulate implies a degree of redundancy of n + 1. In order to avoid

additionally operational restrictions and to allow unrestricted repair, maintenance and testing during

normal operation, one additional redundancy is added, resulting in a n + 2 system configuration (see

figure 7).

This n + 2 requirement leads to a safety system configuration of 4 x 50 % for the most challen-

ging design basis accident. Each train of the safety systems is directly assigned to one main coolant

loop. The safety trains are functionally and physically separated or structurally protected in order to

limit the effects of common cause failures, such as fire or flooding.

62

The emergency core cooling and residual heat removal system takes over cooling of the reactor

core in the event of a loss of coolant accident. The high pressure injection system is able to make-up

small coolant losses by injection of borated water from the borated water storage pools into the hot

legs of the primary circuit.

The low pressure residual heat removal pumps compensate larger losses of coolant and remo-

ve the decay heat in the long term. The trains inject into both, the hot and the cold leg of the primary

circuit The same concept applies for the eight accumulators of which always one is directly assigned

to one hot or one cold leg, respectively. This combined injection has been proven very effective in va-

rious experimental investigations performed in world-wide cooperation.

Another safety system provided in this design, which is a rather unique one in comparison to

competing designs, is the extra borating system, It is also built-up in four independent trains directly

assigned to the four main coolant loops. It injects borated water at high concentration into the primary

circuit to make-up small primary system leakages. It is furthermore used as a second, independent

shutdown system, of special value in the course of Anticipated Transients Without Scram (ATWS).

The same design philosophy as above applies for the emergency feedwater system on the se-

condary side which is also a four train system. Each train is directly assigned to serve one steam ge-

nerator in case of loss of main feedwater. It should be emphasised that the heat removal via thö se-

condary side is a very important feature of the nuclear power plant design described in this paper,

since the reliable and fast heat removal via the steam generators avoids the necessity of feed and

bleed operation on primary side for the mitigation of design basis accidents. This is an additional rea-

son for the provision of a very reliable startup and shutdown system with two 100 % pumps, feeding

feedwater into the steam generators from he feedwater tank during operational startup and shutdown

and during various transients and accidents.

Another very important factor contributing to the high safety standard of our nuclear power

plants is the careful design of the man-machine interfaces. For the mitigation of accidents a reliable

event identification is mandatory. After this identification, event oriented countermeasures have to be

taken. In order to enable the operator to perform a careful analysis, he should be provided with eno-

ugh time to avoid decisions and actions under time pressure. Therefore the so-called 30-minute-

criterion is applied, which means that all actions for the mitigation of any accident are initiated automa-

tically for the first 30 minutes after onset of an accident. Only after this period of time manual counter-

measures by the operators are required.

Probabilistic risk assessments have shown that the overall frequency for accident sequences

beyond design basis is about 1,4 x lO^/year, which is in comparison with other internationally discus-

sed design conditions for future plants, an outstanding good figure. The failure of all relevant safety

functions contribute to this figure almost to the same extent, so that a well balanced safety concept

was realized. Further consideration of plant internal emergency operating procedures, preventive and

irrigative accident mitigation measures reduce the probability of severe radioactive releases to the

environment further to below 10'7/year (see figure 8).

63

CONSTRUCTION AND OPERATING EXPERIENCE

The three KONVOI plants constructed in Germany from 1983 through 1989 were built with an

average construction time of about five years (see figure 9). The excellent operating experience obtai-

ned with these plants so far shall be shown using two very indicative figures. The first is the relative

time the plants were connected to the grid. German plants are better characterized by this figure than

by the load factor, because some German plants contribute to load follow operation in the European

grid. For the KONVOI plants an average service time factor of about 90 % was achieved calculated

from first grid connection to the end of 1992 (see figure 10).

A second very important operational figure demonstrating the high quality of the design with re-

gard to radiation protection is the personnel exposure to the operating personnel. The KONVOI plants

have reached here an average figure of less than 0.3 mSv/year (see figure 11).

CONCLUSION

In case Turkey intends to introduce nuclear energy NPI together with their parent companies Si-

emens and Framatome are prepared to establish a strong consortium in which, besides Siemens and

Framatome, GEC-Alsthom and Turkish companies will participate. The technology offered by this con-

sortium would rely on the German PWR-technology for the nuclear part of the plant. This technology

has been extensively discussed during the negotiations for the AKKUYU project and has proven its li-

censability in Turkey. For the conventional side of the plant GEC-Alsthom, the supplier for the French

conventional islands, will be responsible.

With this technology, we are able to offer the state of the art in Pressurized Water Reactor

Plants. The capabilities and the strength of the partners involved will ensure an efficient implementati-

on of the project.

64

3<Q

Service cooling waterpump houses

Turbinebuilding

Reactor building

Emergencyfeed building

Reactor auxiliarybuilding

Designed to withstand:

[~1~1 Aircraft crash, blast waveand earthquake

I 2 I Earthquake and blast wave

I 3 I Earthquake

j 4 I Aircraft crash(part protection)

Redundancy areas:

3Emergencydieselbuilding

Switchgear building

O ) Vent stack

Building Protection Status and Redundancy Areas for a1300 MW Convoy PWR Nuclear Power Plant

O

r»CO

CO

SIEMENS

A Concrete containmentB Spherical steel containmentC AnnulusD Base plate

E Steam generatorF Fuel poolG Reactor pressure vesselH Main valve compartment

PWR Reactor Building Cross Section n"

55 §• °

Fig-2

66

Nuclear Power Internat ional

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1 Diesel Engine2 Generator3 Gear4 Emergency Feed Pump5 Demineralised Water Pool6 Remote Shutdown Station

Emergency Feed BuildingKONVOI

NPI Nuclear Power International

Power

Thermal Reactor OutputGross Electrical OutputNet Electrical Output

Reactor Coolant System

Number of Coolant LoopsReactor Operating PressureRPV Inlet TemperatureRPV Outlet Temperature

Reactor Pressure Vessel

Inside DiameterCylindrical ShellHeightWeight

Steam Generator

HeightDiameterTube Material

Reactor Coolant Pump

TypeDischarge HeadDesign Flow Rate

Pressurizer

Volume

Containment

DiameterDesign PressureDesign Temperature

3,8501,4471,377

4158

291.8325.2

MWMWMW

bar°C°C

5,000 mm12,362 mm

507 Mg

21,300 mm4,812 mm

Incoloy 800

single stage centrifugal pump89.6 m

4.969 kg/s

65 m"

56 m5.3 bar145 °C

NPI PWR 1400 MW, KONVOI,Main Technical Data

NPt-ME/tmrem

SF/Oiti/otaubpm-3

April 16.1882

Fig-4

ÇjKMfU

Control rod drive mechanism

Control rod guide assembly

Upper support grid

Coolant inlet nozzle

Support columnUpper core plate

Fuel assemblyCore shroud

Pressure vessel

Core barrel

Lower support grid

Flow skirt

Reactor Pressure Vessel and Internals tetom

Fig-5

69

2.1-1 KWU-Steam Generator Design-Highlights

•21300

Forged Material• Reduction of weld length• Reduction of ISI extent• Reduction öf radiation exposure

Feedwater Inlet• Protection against thermal stratification• Welded thermal sleeve '

Feedwater Sparger (J-Tubes)• No dry-out in case of low water level• No waterhammer

Incoloy 800 (Mod.) Tubes• NolGSCC• No other material related corrosion

Tube supports (GRID-Type Design)• Minimization of flow resistance• No deposits on supports• No denting

Flow Distribution Baffle• High velocity on top of tube sheet• Minimization of deposits• Reduced risk for wastage, pitting

Tube to Tubesheet Connection• Welding into primary side cladding• Twofold mechanical expansion• No crevice corrosion

Fig-6

\KWU

— * i

EB EB

DWR 1300 MW Not- u. Nachkühlung 4-Strang KonzeptEmergency Core Cooling Chain 4-Train Concept

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iuclear Power international

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Actuallicensingrequire-ments

Riskreduction

1st level

2nd level

3rd level

4th level

Plant status Measures

ft

' "/ X X"/<"4

Q Quality assuranceQ Personnel qualification• Automation

Operating Disturbances i—Q Inherent safe operationQ InterlockingQ Limitation system

Q Protection system• Safety system• Activity confinement

Control of rare eventsAce. Manag. MeasuresPreventive + Mnigative

• Emergency Oper. Proc.

Multilevel Concept of Plant Safety o

o>S: S>

SIEMENS

1981

Isar2

Emsland

1982

Neckar 2

1983 1984 1985 1986 1987 1988 1989

Construction period (1s t reinforcement forreactor building up to handover)

Contractual date of handover

Actual date of handover

Interruption by court order

Reduction of construction period

Time Schedule for Convoy Plantsa>o

Is

SIEMENS 0084/13

Mean Value 78,8 %

' • ' y ' f : ' . . : > • . • " • " V " • ' • • " • ' • - - , , " • - • . • • . - - . • - • • . " . - - • • ' • • . . • •

% • • • • < : - : . • • • -. • • - • • • • . . • _ • • - . . . •

, ; . . : - : - . , . " : : . . - : - • - " • • . • , - - . . - • • " . ' • . • • • - . • - . - . • -

Mean Value 82,3 %

3!

Load Factor Service Time Factor

Cumulative Load Factor and Service Time Factor of Siemens-PWR-Plantsfrom Commercial Operation up to December 1992

N 162/Ro/21.6.1993

Power International

-4 (Q

I I . .1985 1986 1987 1988 1989 1990 1991

Personnel Exposure in Siemens PWRs NPIC:\LEV\FOL\A LLGEMEI\PERSEXPO.XLS